Purge recovery arrangement for refrigeration systems



June 6, 1961 J. w. ENDRESS ETAL 2,986,894

PURGE RECOVERY ARRANGEMENT FOR REFRIGERATION SYSTEMS Filed Feb. 3, 1958INVENTORS JAMES w. ENDRESS a TERRY M. TOWNSEND BY W ATTORNEY UnitedStates Patent 2,986,894 PURGE RECOVERY ARRANGEMENT FOR REFRIGERATIONSYSTEMS James W. Endress, Syracuse, and Terry M. Townsend,

East Syracuse, N.Y., assignors to Carrier Corporation,

Syracuse, N.Y., a corporation of Delaware Filed Feb. 3, 1958, Ser. No.712,934 6 Claims. (Cl. 62-85) This invention relates to purge-recoveryarrangement for refrigeration systems, more particularly, to anarrangement for purging non-condensable gases from a centrifugalrefrigeration system and recovering from these purged non-condensablegases any refrigeration admixed therewith.

In refrigeration systems such as centrifugal and absorptionrefrigeration systems with time, air, water vapor and other foreignmatter gradually leak into or are formed in the system. This, as is tobe expected, results in a malfunctioning of the system sincenon-condensable gases, for example, interfere with the heat exchangerelation between the refrigerant and condensing or cooled mediums. Waterin such a refrigeration system causes corrosion and also interferes withheat exchange between the refrigerant and condensing or cooled mediums.

A variety of systems have been evolved, designed to purge this foreignmatter from a refrigeration system and to facilitate recovery of anyrefrigerant removed with said foreign matter. For example, some deviceshave employed an auxiliary compression refrigeration system forinitiating flow of the non-condensable gases from the primaryrefrigeration system and for chilling and condensing thesenon-condensable gases. The increased cost of manufacture and subsequentmaintenance arising from the provision of an auxiliary purgerefrigeration system is obvious. Other systems, for example, haveemployed steam and water ejectors which do not permit recovery of therefrigerant.

The present invention provides an arrangement which permits purging of arefrigeration system to remove noncondensable gases and foreign matterfrom the refrigeration system, and thereafter to separate any purgedrefrigerant from the foreign matter and permit return of the refrigerantto the refrigeration system thus assuring that loss of refrigerant dueto the necessary purging operation is a minimum.

It is accordingly a primary object of this invention to provide animproved purge system for refrigeration systems permitting removal ofnon-condensable gases from the refrigeration system, and return to thesystem of any refrigerant admixed with said non-condensable gases thusobviating the loss of refrigerant from the refrigeration system.

Another object of this invention is to provide a purgerecovery system ofa simple nature, having a minimum number of components.

These, and other objects of the invention, which will become apparent inthe following description and claims, are achieved by provision of anovel purge-recovery arrangement including a separation chamber withinwhich a mixture of refrigerant, water and non-condensable gases may beseparated. The mixture is admitted to the separation chamber from thecondenser of the refrigeration system, for example, a centrifugalrefrigeration system, the chamber pressure and temperature beingmaintained during operation lower than pressure and temperature in thecondenser. A cooling coil is placed within the chamber, liquidrefrigerant from the condenser passing through the coil and beingevaporated therein by its heat exchange relation with the gases andvapors passing over the exterior of the coil. Passage of the gases iceover the coil condenses any refrigerant and water vapor present therein,the liquid collecting in a sump below the coil. Since the refrigerant isnot miscible with and is heavier than water, the liquids separate. Therefrigerant is then returned to the refrigeration system; the water canthen be eliminated; and the non-condensable gases are passed off to theatmosphere. A novel valving arrangement is provided controlling theelimination of non-condensable gases from the chamber in response tovariation in pressure differentials between the condenser, separationchamber and evaporator.

A primary feature of the invention relates to the provision of apurge-recovery arrangement for a refrigeration system which permitsautomatic flow of non-condensable gases carrying entrained refrigerantand water vapors from the condenser of the refrigeration system to bepurged, to a separation chamber where the non-condensable gases arecooled to condense refrigerant and water vapors intermingled therewithand then the non-condensable gases are passed off to the atmospherewhile the condensed water is passed off to a water line, and the liquidrefrigerant is separated from the water and returned to therefrigeration system.

Another feature of the invention resides in the fact that the separationchamber is provided with cooling by employing the refrigerant from thecondenser to the refrigeration system, permitting said refrigerant topass through an expansion means to the separation chamber.

The specific construction details of a preferred embodiment of theinvention and their modes of functioning will be made most manifest andparticularly pointed out in conjunction with the accompanying drawing,wherein:

The figure represents a schematic view of the novel purge-recoverysystem shown as applied to a centrifugal refrigeration system.

Referring now more particularly to the drawings, a centrifugalrefrigeration system 10 including the purge-recovery arrangement of thepresent invention is shown. Refrigeration system 10 comprises acompressor 11, a condenser 12 having condenser sump 13 leading to aneconomizer 14 which supplies liquid refrigerant to evaporator or cooler15; liquid refrigerant is flash-cooled in the economizer, the flashedvapor being forwarded to the second stage of compression of compressor11 through line 14', as shown in Jones Patent Number 2,277,647, grantedMarch 24, 1942. In cooler 15, liquid refrigerant is placed in heatexchange relation with a medium to be cooled, refrigerant vapor soformed being forward through line 16 to the first stage of compressionof compressor 11.

From the upper part of condenser 12, a purge line 18, having arestricting orifice 19, strainer 19 and line valve 19", is extended toseparation chamber 20.

Separation chamber 20 is formed by a shell or casing 21. A condensingcoil 23 is placed, preferably, in the upper part of the casing adjacentthe purge line inlet so that gases entering the casing are passed overthe coil in heat exchange relation with refrigerant passing through. thecoil thereby condensing any refrigerant or water vapor carried by thenon-condensable gases to separate the refrigerant and water from thenon-condensable gases.

A separation deck 22 is placed below coil 23 and re- A refrigerantgenerally employed in centrifugal refrigeration systems isdichlorodifiuoromethane which is not miscible with"- ceives the liquidcondensed by the coil.

water and is heavier than water. Thus in the separation deck, the liquidrefrigerant separates from the water and passes through passageway 20 tothe sump in the bottom of casing 21. A weir 26 regulates the volume ofliquid, refrigerant passing to the sump and prevents passage of I waterdue. to difference in density and immiscibility of the. water. A floatvalve 24 placed in the sump regulates pas-f Patented June 6, 1961assesses;

sage of liquid refrigerant from the sump through line 35 to the cooler15. An equalizer tube 25 is formed in deck 22 and is provided with oneor more openings in order that pressure in the upper and lower portionsof the casing are equalized during operation.

Water collects in deck 22 as it separates from theliquid refrigerant andeventually overflows weir 60 of deck 22 to sump 61. A sight glass 62 isplaced adjacent sump 61 so that an operator may check the volume ofwater collected in sump 61. Water line 30 controlled by valve 31 isconnected to sump 61. As water collects in sump 61, valve 31 is operatedby the operator permitting water to drain from the sump to waste.

Atmospheric line 27 leads from the separation chamber casing 21 and isprovided with a normally closed solenoid relief valve 28 for the reliefof non-condensable gases which collect in chamber 20. Control of valve28 will. be explained hereafter.

Liquid refrigerant supply line40 is connected from the sump 13 ofcondenser 12 to the cooling coil 23 within separation chamber casing 21.Suitable expansion means such as temperature controlled expansion valve41 or back pressure valve (not shown) is provided in the liquidrefrigerant supply line 40 to control supply of refrigerant to coil 23.It will be understood expansion means 41. operates to maintain a desiredcoil temperature to prevent collection of frost or ice thereon or inthe. separation chamber. A temperature responsive control 42 (here shownin the form of a bulb and capillary tube) is connected to valve 41 toregulate the action'thereof. If'desired, as shown, the bulb may beplaced on the'refrigerant leaving line 50 of coil 23 which in effectconstitutes the suction line. The refrigerant after passagethrough coil23 is forwarded to the cooler through line 50.

Solenoid valve 28 is controlled by means of two differential pressureswitches 55, 56 placed in series in an electrical circuit includingvalve 28. Switch 55 is connected to the condenser 12 by line 70 and tochamber by line 71 so that it responds to the difference in pressuretherein. Switch 56 is connected to the condenser 12 by line'70 and tosuction line 50 or cooler 15 by line 73 so that it responds to thedifference in pressure between cooler pressure and condenser pressure.Both switches 55, 56 are atfected by such pressure differentials tocontrol opening and closing of valve 28. Preferably, the switches are inseries with each other and the main starter holding coil of therefrigeration system so that the switches are enersure differential andto open at sixteen pounds per square inch pressure differential.

The switches are shown diagrammatically. switches are the same exceptthat switch 55 is normally closed and switch 56 is normally open. Eachincludes a first bellows 75, and a second bellows 76 connected by a rod77. A lever 78 is attached to rod 77 and is pivoted"- at point 79. Thusas the pressure differential reflected by'bellows 75, 76 moves rod 77lever 78 pivots about' point 79 to move switch arm 80 toward or fromcontacts 81 breaking or closing the'circuit. The differential pres sureswitches employed may be manufacture by Penn Controls, Inc., of Goshen,Indiana, the normally closed switch being sold commercially as typeI-IKOGBAIOZ'. and the normally open switchbeing-sold commerciallyastype-HKO6BA104.

Operation The novel purge-recovery. system abovedisclosed is employedpreferably in connection with the condenser of I acentrifugalrefrigeration system in which during opera tion condensing pressureisgenerally above atmosphenc pressure;-

Both

The primary function of the purge-recovery system is to removenon-'condensable gases and water" condenser. When the system is placedin operation, the

compressor'quickly pulls-down so that a substantial pres sure differenceexists between the condenser 12 and chamber 20. The greater pressure incondenser 12 forces the non-condensable gases and mixed refrigerant andwater vapors through the line 18, orifice 19, and strainer 19', valve19"being open, and over cooling coil 23, thus condensing vapors by the heatexchange relation with therefrigerant in the coil, refrigerant in thecoil evaporating and passing through line 50 to cooler 15. Valve 41regulates the supply of refrigerant to coil 23.

The non-condensable gases collect in the top of the separation chamberand may be released to the atmosphere through atmospheric line 27. Thecondensed vapors,.liquid refrigerant and water are collectedbelowcondensing coil 23 is separation deck 22. In the sepa ration deck.22 the liquid refrigerant separates from the water, the heavierrefrigerant settling to the bottom and. passing over weir 26 beneath theseparation deck to the' refrigerant sump in the bottom of chamber 20. Itwillv be observed that float valve 24- will open when it isbuoyed up toa sufficient height by a depth of refrigerant suflicient to permitopening the discharge refrigeration.

line 35, without backup of refrigerant from the evaporator.

The lighter water normally accumulates at the top of the separationdeck, overflows weir 60, collectsin the water sump and is dischargedthrough water line 30 by means of manual valve 31.

In operation, the novel purge recovery unit is provided with controls soas to permit automatic purging of the.

refrigeration system. Condenser-separation chamber differential pressureswitch 55, and condenser evaporator switch 56'are both energized atstart-up of the refrigeration system 10, since switches 55 and 56preferably are in series with the main starter holding coil. When thepressures are substantially equal in the condenser 12, separationchamber 20, and evaporator 15, as at start-up, switch 55 is closed, andswitch 56 is open. So long as either of switches 55 or 56 is open,atmospheric valve 28 remains closed. When the condenser pressure buildsup under normal refrigeration system operation switch 56 closes, thuscompleting the circuit to the solenoid of valve 28. opening the same,and permitting discharge of non-condensable gases through. atmosphericline 27 from separation chamber 20 to the atmosphere.

The resultant decrease in pressure in separation chamber 20' results ina pressure differentialv between the separation chamber and thecondenser producing purge ing of the non-condensables from thecondenser. Switch- 55 responds to this pressure differentialdeenergizing the solenoid of valve 28' thus closing relief valve28, per:

mitting an increase in separation chamber pressure. This cycleis'repeated'during operation of the refrigeration system;

The present "invention provides'a novel purge-recovery" system foruse inremoving non-condensable gases from refrigeration'systems, and'returningto the refrigeration system refrigerant admixed with the purged non-condensable gases. The arrangement functions by meansof" pressurediiferentials in the condenser of the refrigeration system andtheseparator of the purge system. to accomplish' automatic purging, withoutnecessitating the use of conventionally employed auxiliary refrigerationapparatus such as compressors, air cooled condensers and the like.

The above disclosure has been given by way of illustration andelucidation, and not by way of limitation; and itis desired toprotecfallembodimentsof the herein dis closed inventive concept withinthe scope of the appended claims.

We claim:

1. In combination with a refrigeration system, a purging arrangement topurge non-condensable gases fromthe system and to recover refrigerantmixed with the noncondensable gases, said arrangement comprising acasing forming a chamber, a line connecting the chamber with thecondenser to permit flow of non-cendensable gases and entrained vapor tothe chamber from the condenser, a heat exchanger placed in the path offlow of the gases, at second line connecting the heat exchanger with thecondenser to supply liquid refrigerant to the heat exchanger from thecondenser, means in said second line regulating supply of refrigerant tothe heat exchanger, non-condensable gases carrying entrained vaporflowing over the heat exchanger in heat exchange relation withrefrigerant therein to condense vapor carried thereby thus separatingthe same from the non-condensable gases, athird line connecting theoutlet of the heat exchanger to the evaporator'of the refrigerationsystem to forward refrigerant from the heat exchanger to the evaporator,means to return condensate directly to the evaporator, and meansgoverning release of non-condensable gases from the chamber, saidgoverning means including a line connecting the chamber with ambietatmosphere, a valve in said line governing passage of non-condensablegases to the line and a control for said valve including a memberresponsive to predetermined variation in the difference in pressurebetween condenser pressure and chamber pressure to actuate the valve andsaid control further including a second member responsive topredetermined variation in the difference in pressure between thecondenser pressure and the evaporator pressure to actuate the valve.

2. A purging arrangement according to claim 1 in which the valve in saidline is a solenoid valve, the first member is a first pressuredifferential switch and the second member is a pressure differentialswitch, the first and second members being placed in an electricalcircuit with said valve, the first switch responding to predeterminedvariation in the difference in pressure between condenser pressure andchamber pressure, the second switch responding to a predeterminedvariation in the difference in pressure between condenser pressure andevaporator pressure whereby, upon startup, the first switch is closedand the second switch is open, the second switch closing upon apredetermined variation in the diflerence in pressure between condenserpressure and evaporator pressure being attained to energize the valve topermit noncondensable gases to flow from the chamber, the first switchremaining closed until a predetermined variation in pressure differencebetween condenser pressure and chamber pressure is attained, thenopening to de-energize the valve and remaining open until a furtherpredetermined variation in pressure difference between condenserpressure and chamber pressure is attained, then again closing toenergize the valve to permit non-condensable gases to flow from thechamber, actuation of the first switch repeating cyclically throughoutoperation of the system.

3. In combination with a refrigeration system, a purging arrangement topurge non-condensable gases from the system and to recover refrigerantmixed with the noncondensable gases, said arrangement comprising acasing forming a chamber, a line connecting the chamber with thecondenser to permit flow of non-cendensable gases and entrained waterand refrigerant vapors to the chamber from the condenser, a heatexchanger placed in the path of flow of the gases, a second lineconnecting the heat exchanger with the condenser to supply liquidrefrigerant to the heat exchanger from the condenser, means in said lineregulating supply of refrigerant to the heat exchanger, non-condensablegases carrying entrained vapor flowing over the heat exchanger in heatexchange relation.withrefrigerant therein to condense refrigerant andwater vapors carried thereby, thus separating the same from thenon-condensable gases, means in the casing for separating liquidrefrigerant from water, means to remove the water from the casing, athird line connecting the outlet of the heat exchanger to the evaporatorto forward refrigerant from the heat exchanger to the evaporator, meansto return liquid refrigerant from the casing to the evaporator and meansgoverning release of noncondensable gases from the chamber, saidgoverning means including a line connecting the chamber with ambientatmosphere, a valve in said line governing passage of non-condensablegases through the line and a control for said valve, said controlincluding a member responsive to predetermined variation in the pressurebetween condenser pressure and chamber pressure to actuate the valve,said control means further including a second member responsive topredetermined variation in the difference in pressure between condenserpressure and evap orator pressure to actuate the valve.

4. In combination with a refrigeration system, a purging arrangement topurge non-condensable gases from the system and to recover refrigerantmixed with the noncondensable gases, said arrangement comprising acasing forming a chamber, a line connecting the chamber with thecondenser to permit flow of non-condensable gases and entrained waterand refrigerant vapors to the chamber from the condenser, a heatexchanger placed in the path of flow of the gases, a second lineconnecting the heat exchanger with the condenser to supply liquidrefrigerant to the heat exchanger from the condenser, means in said lineregulating supply of refrigerant to the heat exchanger, non-condensablegases carrying entrained vapor flowing over the heat exchanger in heatexchange relation with refrigerant therein to condense refrigerant andwater vapors carried thereby, thus separating the same from thenon-condensable gases, means in the casing for separating liquidrefrigerant from water, means to remove the water from the casing, athird line connecting the outlet of the heat exchanger to the evaporatorto forward refrigerant from the heat exchanger to the evaporator, meansto return liquid refrigerant from the casing to the evaporator and meansgoverning release of non-condensable gases from the chamber, saidgoverning means comprising a line connecting the chamber with ambientatmosphere, a solenoid valve in said line governing passage ofnon-condensable gases through the line and control means for said valveincluding a first pressure differential switch and a second pressuredifferential switch placed in an electrical circuit with said valve, thefirst switch responding to a predetermined variation in pressuredifierence between condenser pressure and chamber pressure, the secondswitch responding to a predetermined variation in difference in pressurebetween condenser pressure and evaporator pressure, whereby, uponstartup, the first switch is closed and the second switch is opened, thesecond switch closing upon a predetermined difference in pressurebetween condenser pressure and evaporator pressure being attained toenergize the valve to permit noncondensable gases to flow from thechamber, the first switch remaining closed until a predeterminedvariation in difference in pressure between condenser pressure andchamber pressure is attained and then opening to deenergize the valveand remaining open until a further predetermined variation in differencein pressure between condenser pressure and chamber pressure is attained,then closing to energize the valve to permit non-condensable gases toflow from the chamber, actuation of the first switch repeatingcyclically throughout operation of the system.

5. A method of purging a refrigeration system to remove non-condensablegases and water from the system and to recover refrigerant mixed withthe non-condensable gases and water in which the steps consist incollecting the non-condensable gases in a first portion oftlie system;removing, the non=condnsable gaseswzar ryin'g entrained refrigerant'vapor'and' water vapor to-a' second *pm'tion'of the system, placing)IiquidTefrigerant" from the first portion of the-system'in heatexchangerelation with the non-condensable gasesand vapors in the" secondportion of the system to condense the vapors, separating refrigerantcondensate from water in the second portion of the system, supplyingtherefrigerant condensate to a third portion of the system to cm-' pensatefor a heat load imposed onthe system, removing water from the secondportion of the system, and in response to predetrernined variation inditferenceinpressure between pressure in'the first portion and pres surein the second portion, purging non condensable gases from the secondportion of the system, andpurging at start-up of'the system,non-condensable gases from the second portion of the system'in responseto predetermined variation indifference in pressure between pressurein'the'first portion of theisystem and 'pressure' inthe-tliird' portion ofthe system.

predetermined variation in' pressure difference between; pressure inthecondenser and'pressure in the evaporator" ofthe refrigeration system,purgingth'e non-condensable' gases 'from the system;

References Cited in the file ofthis patent UNITED; STATES PATENTS1,636,512 Hil'ger Jilly 19, 1927 l,884,312' Sloan Oct; 1932 2,062,697Buehler Dec. 1, 1936 2,249,622 Schlumb'ohm July 15,; 1941 2,321,964Zieber: June 15', 194-3 2,450Q707 ZwiCkl' Oct; 5; 1948 UNITED STATESPATENT oE IcE CERTIFICATE OF CORRECTION Patent No, 2,986,894 June 6,1961 James W; Endress et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2, line 26, for "to the" read of the column 3, line 39, for"pressure" read pressures line 63, for "manufacture" read manufacturedcolumn 4, line 51, strike out "the"; column 5, line 26, for "amhiet"read ambient column 7, line 12, for "predetremined" read predeterminedSigned and sealed this 5th day of December 1961, v

(SEAL) Attest: V

ERNEST W. SWIDER DAVID L. LADD Attesting Gfficer Commissioner of PatentsUSCOMM-DC

